Clients not showing up in DHCP Client list

A friend of mine has an ethernet network at his workplace. It uses a
Linksys router, netgear hub and has 4 Macs running System 10, and 3 PC's
running XP sp2, and two printers ( a brother and an HP). they have cable
modem access to Internet.

The network was quite stable for nearly two years, then all of a sudden
problems started developing. Some of the Mac's were unable to print, and
it seems that at one time or another the networked computers also lost
connectivity to the Internet, although not necessarily all at the same
time.

I suggested that they reboot everything and see if that didn't correct
the problem. My assumption was that maybe RoadRunner had changed their
IP address and the router was getting confused because of it. In any
case, rebooting the cable modem, router and all the computers seemed to
fix things...for a few days. then the problems came back.

I used the Linksys webadmin to peer into the DHCP client list and
noticed that on one occasion, only one computer was listed, even though
4 computers were "online" and able to surf the net, etc. So I'm
wondering how it's possible that they apparently had Internet access yet
haven't apparently been assigned an IP address by the router. Is this
even possible?

Any ideas what might be going on here? We've been trying to isolate this
problem for over two months and don't know if it's a failing router,
hub, bad ethernet cable, or some combination of all of the above, or
something else that I don't know about (which is HIGHLY probable)

Appreciate any suggestions.

Michael

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On Sat, 01 Apr 2006 13:28:56 GMT, in alt.internet.wireless , Michael
Erb <(E-Mail Removed)> wrote:

>I used the Linksys webadmin to peer into the DHCP client list and
>noticed that on one occasion, only one computer was listed, even though
>4 computers were "online" and able to surf the net, etc. So I'm
>wondering how it's possible that they apparently had Internet access yet
>haven't apparently been assigned an IP address by the router. Is this
>even possible?

More likely, they have got IPs correctly, but the web admin tool isn't
correctly noticing this fact. My SMC has the same 'feature' and it
works just about as well.

>Any ideas what might be going on here? We've been trying to isolate this
>problem for over two months and don't know if it's a failing router,

Don't worry about it, its probably just a bug in the router admin
tool's s/w.
Mark McIntyre
--

Michael Erb <(E-Mail Removed)> hath wroth:

>I used the Linksys webadmin to peer into the DHCP client list and
>noticed that on one occasion, only one computer was listed, even though
>4 computers were "online" and able to surf the net, etc. So I'm
>wondering how it's possible that they apparently had Internet access yet
>haven't apparently been assigned an IP address by the router. Is this
>even possible?

That's normal. What happens is that the ARP table in your unspecified
Linksys router only displays entries for DHCP assigned IP's just after
they are assigned. If you reboot the router, the table is cleared and
you'll see nothing. When it comes time for the client to request a
lease renewal, the router will first ping the IP address to see if
it's being used. It will then grab the MAC address to see if it
matches one that was assigned to another IP address. If everything is
correct, the router DHCP server will renew the lease.

Depending on implimentation, it may or may not show the renewal in the
client list. I've lost track of which routers do what, but some of
them will only show the lease when originally issued. Others will
also show them on a lease renewal. In either case, the router does
not need to know the IP addresses issued by DHCP until lease renewal
time comes around. The client has a valid IP address and can use it
whether it's displayed or not.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Thanks guys. That's very good information to have.

Michael

"Jeff Liebermann" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...

> That's normal. What happens is that the ARP table in your unspecified
> Linksys router only displays entries for DHCP assigned IP's just after
> they are assigned. If you reboot the router, the table is cleared and
> you'll see nothing. When it comes time for the client to request a
> lease renewal, the router will first ping the IP address to see if
> it's being used. It will then grab the MAC address to see if it
> matches one that was assigned to another IP address. If everything is
> correct, the router DHCP server will renew the lease.
>
> Depending on implimentation, it may or may not show the renewal in the
> client list. I've lost track of which routers do what, but some of
> them will only show the lease when originally issued. Others will
> also show them on a lease renewal. In either case, the router does
> not need to know the IP addresses issued by DHCP until lease renewal
> time comes around. The client has a valid IP address and can use it
> whether it's displayed or not.
>
> --
> Jeff Liebermann (E-Mail Removed)
> 150 Felker St #D http://www.LearnByDestroying.com
> Santa Cruz CA 95060 http://802.11junk.com
> Skype: JeffLiebermann AE6KS 831-336-2558